Apparatus for production of gas



2 Sheets-Sheet l H. BAETZ Filed May 16, 1940 APPARATUS FOR `PRODUCTIONOF GAS Aug. is, 1942.

Aug.l 18, 1942. H. BAETZ APPARATUS FOR PRODUCTION OF' GAS Filed May 16,1940 2 Asheets-sheet 2 Pateniecl Aug. 18, 1942 UNITED STATES PATENTOFFIQE APPARATUS FOR PRODUCTION OF GAS Henry Bactz, Brookline, Mass.

Application May 16, 1940, Serial No. 335,551

8 Claims.

This invention relates to methods of and apparatus for the production ofgas, and particularly where high temperatures are necessary in itsproduction. The principles of the invention are applicable to a widevariety of uses but they are herein shown for illustration as applied toa high temperature vapor-phase cracking still for the cracking ofpetroleum, such that toluol and other aromatic fractions of petroleumoil which require relatively high cracking temperatures may be obtainedin a practical manner.

In the described embodiment of the invention submitted for illustration,a high temperature vapor-phase cracking still is shown presenting a pathof travel for the oil through a tubular conduit. In the case of tubularVconduits heretofore used for similar purposes, where the maintenance oftemperatures in excess of 1000F. has been attempted, serious diflcultieshave been encountered due to the rapid formation of carbon, which soonlls and chokes up the tubes so that the still has to be shut down withgreat frequency until the tubes have been opened and cleaned and thecarbon removed. The consequent dismantling of the parts involves expenseand a loss of f time and makes the process relatively inefcient.

I have found that this rapid and excessive formation of carbon ispromoted by .an unnecessary prolongation of the cracking operation. The

difficulties heretofore experienced in that respect are due in part tothe relatively low velocity under which the oil travels through thetubular conduits serving to transfer the cracking heat to the oil,

and in part to the relatively low heating capacity pediting andhastening the cracking operation,

this by increasing the velocity of travel of the oil through the conduitand by greatly increasing the exposed area of the heat transfer walls ofthe conduit in proportion to the volume of oil enclosed by such walls. l

Another object of the invention is to provide a cracking still with suchprovision that the carbon, when and as formed within the passages of thetubular conduits, may be quickly removed without opening or dismantlingthe tubes, this being accomplished by the action of steam or waterdirected against the carbon while an adequate temperature is maintainedabout the tubular conduits to result in the formation of water gas,whichis thereupon conducted through and dischargedfrom the still.

In the drawings:

Fig. 1 is an elevation, partly in section, showing a tubular crackingstill embodying one form of the invention;

Fig. 2 is a section in plan on the line 2--2 in Fig. 1;

Fig. 3 is an enlarged detail in sectional elevation, partly broken away,showing the construction of each tubular conduit;

Fig. 4 is a cross-section of the tubular conduit in plan taken on theline 4 4 in Fig. 3; and

Fig.5 is a detail showing one of the curved vanes introduced into theannular space presented by the tubular conduit to impart a rotarymovement to the petroleum. Referring to the drawings and to theillustrative embodiment of the invention there shown, the still iscontained Within a walled casing of refractory material forming theheating chamber of the still and comprising the end walls I, side walls9, and top and bottom walls II and I3, the casing being supported on abase I5 by vertical steel buck-stays or I-beams I'I.

At one end there is provided a combustion chamber I9 to serve as `asource of heat for the still, this chamber being also constructed ofrefractory material. Any suitable fuel may be used, but herein there isshown for that purpose a conventional oil burner 2|. The products ofcombustion pass over the baiiie plate 23 through an opening 25 in theadjacent end wall 1 of the casing and into the still chamber formedwithin the casing.

The still chamber is sub-divided into successive c'cmpartments by aseries of baille walls 21 and'29, also of refractory material. Thesewalls are arranged in alternation, the iirst of which 2'I extendsupwardly from the bottom wall I3 of the chamber but terminates short ofthe topwall, and the secondof which 29 extends downwardly from the topwall'but terminates short of the bottom wall, the succeeding baillewalls being similarly arranged in alternation. The result is that theproducts of combustion from the furnace have a continuous path upwardlythrough the first compartment, then downwardly into and through thesecond compartment, upwardly through the third compartment, and so on,until they pass out of the still chamber through the flue exit 3 I' forthe waste gases at the top of the last compartment.

In each compartment of the still chamber, and exposed to the heat of theproducts of combustion, there is positioned an upright tubular conduitthrough which the petroleum oil is caused to travel in a directioncounter to that of the flow of the heated combustion products, the tubesbeing so related as to provide for a continuous flow ofv their contentsfrom one end of the still to the other, as will be more fully described.Where reference is made to the flow or travel of the oil, it will beunderstood that the latter term includes the oil either in its enteringliquid state or its subsequent gaseous state.

The several successive tubular conduits are of substantially the sameconstruction, the latter being shown more in detail in Fig. 3. Eachconduit consists of an outer tubular member 33 having a flange 35 ateach opposite end. When installed in the still this tube, as shown inIFig. 1, extends from the bottom wall to the top wall of the stillcasing.

At its bottom this tubular member is bolted to a companion iiange 31carrying a cap-like extension 39 and constituting a closure for thebottom of the tube 33.

At its top the flange 35 of the tubular member is bolted to a flange 4Iwhich carries a second tubular member 43 constituting in effect anextension of the tube 33 but contracted at its top to close the space 45within the tube 43. At the side of the tubular extension is a pipeconnection 41 through which for certain of the tubes the oil to undergocracking is admitted and for others it is disch-arged.

The passage through which the oil travels is provided by an annularspace 49 (Figs. 3 and 4) formed between the outer tube 33 and an innertube 5|. This provides a double-Walled annular passage for the oil ofrelatively small crosssectional area as compared with circumferentialsurface presented to the oil by the outertube 33, the walls of which areexposed to the heat of the products of combustion of the surroundingheating compartment. The inner walls of the tube 33 may be spaced soclosely from the outer walls of the tube 5| as to provide a relativelyhigh capacity forthe transfer of heatto the oil within the annularspace.

Such heating capacity is substantially inversely proportional to thefactor represented by the cross-sectional area of the annular passagethrough which the oil flows divided by the inside perimeter of the outertube.

For example, with an outer tube having an inside diameter of 5%, inchesand an inner tube 5| having an outside diameter of 4% inches, the

width of the annular space through which the Aouter tube from the innertube.

of the proportions indicated in the described still, the velocity oftravel of the oil through the conduit is correspondingly increased forany given volume of oil fed through the still.

The inner tube 5I has its lower end, which may be either closed or open,extending nearly but not quite to the closed bottom of the outer tubecap piece 33 to maintain the annular passage throughout substantiallythe full length of the tube 33'. At its upper end, just above the flange4|, the inner tube 5| is contracted and its end closed about andsupported by the still smaller innermost tube 53. The latter extendssubstantially the full length of the tubular conduit and has its lowerend opening into the space provided by the cap-like extensionl 39. Thisprovides a counter flow path of travel for the oil which passes down orup through the annular passage 49, as the case may be.

vThe cross-section of the passage presented by the innermost tube 53 ispreferably not materially different from that presented by the annularpassage 49 between the outer tube 33 and the next inner tube 5|, so thatthere is no change in the velocity of flow of the oil but asubstantially uniform velocity is maintained under all conditions. TheVsmall inner tube Yin turn passes through and is fastened to thecontracted end of the tube extension 43 and its protruding end isconnected to the curved tubular pipe 55, by which communication is hadto the next tubular conduit of the series. In the travel of the oilthrough the conduit the space between the innermost tube 53 and theenclosing tube 5I remains as a dead or inactive space.

The several tubular members which form the conduits for the oil areformed of heat resisting metal, such, for example, as a chromium molybdenum steel alloy.

When installed in the still chamber, the upper part of each tubular-conduit passes through a surrounding disk-shaped block 51 of refractorymaterial which fits closely into an opening in the top Wall. This blocksurrounds and protects the bolts of the flanges 35 and 4| but is formedin segments so that on removal of the conduit the flange boltsare-accessible for separating the Each conduit is supported by Vone ormore horizontal supporting members 58, shown partly broken away, towhich the tubular extension 43 of the conduit is attached byconnections, the details of which are not herein shown.

square inches, so that the factor referred to is 'to secure the requiredheat transference for the oil the ratio of the cross-sectional area ofthe annular passage to its outside perimeter with which Vthe oilcontacts should be not more than 1.0.V

It will be seen that with an annular passage At the bottom end theflanges 35 and 31 of each tubularconduit are protected by a similardisk-shaped block Y59 of refractory material which has a close fit in.an opening 3| in the bottom wall |73 of the casing but is slidabletherein so that expansion and contraction of the suspended tube mayreadily take place while the still is in operation. The tubes near thefurnace end of. the still are subject to higher temperatures than thoseat the opposite end of the chamber and successive tubes therefore tendto expand unequally. Since each tube presents passages for a two-waytravel of the oil, communieating connectionsV are required only at thetop of the conduits, no connections being necessary be tween the bottomsof the tubes, and such un equal expansion movements accordingly mayreadily take place, each tube adapting itself to the heat expansionrequirements independently of the others.

The opening 6| in the bottom wall I3 is closed by a refractory cover 63resting on the support 65. By displacing this support, the cover may beremoved and access had to the bottom of the conduit.

By disconnecting the pipe connections 55 and 41 the entire tubularconduit may belifted from the outer chamber and the outer tube 33separated from the inner tube for the purpose of replacing a burned outtube or for any other purpose.

In the operation of the cracking still, the oil is delivered from anysuitable source of supply (not shown) to the feed pipe 61 and forced bythe pump 69 through the pipe connection 41 into the chamber 45 of thetube extension 43 for the first tubular conduit, or that located in thelast of the several heating compartments of the still. The pressureemployed will depend more or less on the length and the cross-sectionalarea of the passages provided by the series of conduits, the pressureused and the cross-sectional area of such passages, however, beingpreferably selected to impart a relatively high velocity to the oil. Asan example, a pressure of from to 50 pounds per square inch may beemployed in a still of the type illustrated. I

From the chamber 45 the oil travels down into and through the annularpassage 49 into the cap-like extension 39, thence into and upwardthrough the small innermost tube 53. In initially entering the top ofthe annular passage, the oil preferably has imparted to it a turbulentrotary path of travel by one or more curved.' vanes 1| (Fig. 5), each ofwhich is Welded to the outer walls of the inner tube 5|, so that the oilmay have contact with all sides of the tube 33. A number of these vanesmay be employed, distributed lengthwise the tube 5|.

From the top of the innermost tube 53, the oil then passes through thecurved connecting pipe 55 into the next tubular conduit of the series.Here, however, its path of travel is first downward through theinnermost small tube 53 into the cap extension 39, and thence into andupward through the annular passage 49, between the outer tube 33 and theinner tube 5| Curved vanes similar to the vane 1| vmay be located in theannular passage 4'9 where the oil initially enters that passage from thetube 53.

At the top of this second conduit the oil passes into the chamber 45,and thence through the connection 41 into the space 45 of the next, andherein the third, tubular conduit of the series, where the path of theoil is substantially the same as in the case of the rst tubular conduit.

It will thus be seen that the travel of the oil through the annularpassage 49 is reversed in the case of successive conduits and thecounterow of the oil through the innermost tube 53 undergoes a similarreversal (as indicated by the arrows in Fig. l), the oil beingtransferred from the first conduit to the next succeeding conduitthrough the curved connecting pipe 55, from the second to the thirdthrough the pipe connection 41, and so on in alternation.

The oil in gaseous state is finally discharged from the last conduit ofthe still through the discharge pipe 13 and passes to a suitablefractionating tower, where the various fractions are cooled down to aliquefying temperature and separately withdrawn. Such tower may be ofany common or usual construction and the specific character of thelatter forms no part of the present invention.

In the operation of the still, the burner 21, which is subject tosuitable control, conventionally indi- 'water gas.

cated .by the valve 15, is operated .under conditions to provide thehigh cracking temperaturesrequired. For example, the temperature of theproducts of combustion where they enter the first heating compartment ofthe still may be maintained at a range approximately of the order offrom 2500" to 3000 F., and since the travel of the oil in successiveconduits is counter to that of the products of combustion throughsuccessive heating compartments, this may be adjusted to maintain anapproximately uniform temperature difference between the oil in any oneconduit and the products of combustion in the surrounding heatingchamber, with a, temperature maintained in the last heating chamber, forexample, of the order of 1000 F.

In the cracking of petroleum oil to produce such fractions as toluol,xylol, benzol, and other like aromatic constituents, high temperatureswell in excess of 1000 are necessary. While the oil travels rapidlyunder relatively high velocity through the relatively restricted annularpassages presented by the series of tubular conduits, due to theeffective heat transfer walls of the latter, there results a uniformlyincreasing absorption of heat by the oil so that before reaching theexit end of the still it may acquire cracking temperatures of the orderof from 1000" to 1500" F. or more as required. i

The high velocity of the oil and the large effective heating capacityprovided by the annular passage in the described form of still not onlymeet the conditions required for effective cracking of such constituentsas toluol and the like, but the expedition with which the cracking isperformed materially cuts down the formation of carbon within the oilpassages. When and as such carbon is formed, however, the constructionof the still lends itself to a simple method of removing the carbonwithout the necessity of dismantling the still or any of its componentparts.

To effect this result the pressure of the oil as it leaves the still isindicated by a pressure gage 11. This indicated pressure has a definiterelation to the pressure under which the oil is forced into the still solong as the oil passages through the tubular conduits are open and freefrom carbon. As soon as carbon forms, however, this condition isindicated by the drop in the pressure at the gage 11, or it may beindicated through a similar gage by a rise in pressure at the inlet end.When this occurs, or where it has proceeded to a stage indicating aninterference with the cracking operation, the feed of oil to the stillis cut off by the valve 19, and the oil valve 8| at the discharge end isalso closed, cutting the still out of cracking operation.

The carbon is then removed by the formation of This is accomplished byforcing through the still, from any suitable source of'supply, water, orsteam if the latter is available, and where water is referred to it willbe understood as including water either in its liquid state or in itsvapor state as steam. The water is forced into the still through theValve-controlled pipe 83 tothe connecting pipe 41 of the rst tubularconduit. The operation of the furnace is at the same time continued tomaintain temperatures in the successive heating compartments suiiicientto generate water gas through the action of the steam on the carbon. Ifwater is introduced in liquid state it promptly becomes steam afterentering the first tubular conduit. The steam passing through thesuccessive conduits acts on the carbon in the passages thereof, with theformation near'the oil exit end thereof, where the temperature impartedto the oil is much higher.. The removal of the carbon by steam or waterand the .formation of water gas require a temperatureof the .order offrom approximately 1100 t0 1800 F.' With the furnace in full operation,and Where the steam or water is admitted as described through the supplypipe 83, this temperature is readily imparted to the steam by the timeit has reached the tubular conduits .near the middle portion of thestill or .at the oil exit end thereof, where the tendency to carbonformation is the greatest.

Under this condition, however7 the 'heat absorbed'by the steam in thefirst few tubular conduits near the oil inlet end of the still may notbesuflicient to effect the formation of Water gas and the removal of thelighter deposits -of carbon in these conduits. In the practicalapplication of this method of carbon removal, therefore, and to effectthe complete removal of all carbon, it may be desirable, after forcingthe steam from the pipe 83 through the still and discharging theresulting water gas through the pipe 85, to insure the removal of thelighter deposits'near the oil inlet lend ofl theV still by reversing thedescribed process.

That is to' say, steam or water is thereafter additionally forcedthrough the still from vthe oil outlet end to the oil inlet end thereof,using for that purpose the pipe 85 to introduce the steam into the stilland the pipe 83 as a discharge pipe for the steam and the resultingWater gas. By that subsequent step, the steam, before reaching' theconduits near the oil inlet end of the still, has reached a temperaturesulicient toinsure the removal of these lighter Ydeposits of carbon.

The gas producing apparatus described, while having useful applicationto the cracking of oil and the production of aromatic constituentsthereof, may also be advantageously used in the production of othergases, such, for example, as Water gas.

While I have herein shown and described for purposes of illustration onespecic embodiment of the invention, it is to be understood that variousother applications of the invention may be made and that extensivedeviations in the form and relative arrangement of parts may also bemade, all without departing from the spirit of the invention.

Iclaim; Y

1.AIn a high temperature vapor-phase oil cracking still, the combinationwith a combustion chamber, of a heating chamber through which theproducts of combustion pass, said heating chamber having baie wallsdividing the same into compartments through which said products ofcombustion pass successively, first in one direction and then in theopposite direction, a series of tubular conduits in successivecompartments comprising each an outer tubular mem- -ber exposed to theheat thereof and having one end closed, an inner tubular memberpresenting saidconduit presenting also an annular passage surrounded bythe walls of said heat exposed outer tubular member and itselfsurrounding and communicating adjacent its closed end with the passageof said inner Vtubular member andY presenting thereby anv outercounter-flow path for the travel of the oil in a direction opposite tothat traveled in said inner passage and in a direction opposite to thatof the travel of the products of combustion, the cross-sectional areasof theV annular and the inner passages being approximately the same, andcommunicating connections between said successive conduits at the-sameAadjacent ends thereof to cause travel of oil through the annularpassage of onel conduit 'in one directionand through the annular passageofthe next conduit in theopplosite direction, the ends of said conduitsopposite' said communicating connections being free to Amoveindependently of `each other in response-to expansion-and contractionunder heat.' i

2. In a gas generator, a` heatingchamber, a tubular conduit in `saidYheating chamber "and having a closed end,'the walls of said conduitbeing exposed -to `-the heatof said chamberfa'nd said conduit having aninner tubular member within said vfirst tubular member opening' intosaid conduit near the closed end thereof, and an intermediate tubularmember between said inner member and said conduit member,vclosed to thetravel of the gas therethrough but'positioned to leave an'annularpassage of relatively small cross-section between the outerwalls of said intermediate member and the inner walls of said tubularconduit member.

3. In a high temperature vapor-phase oil cracking still, the combinationwith a Vheating chamber, of a series of tubular conduits in saidchamber, each conduit: presenting an Vannular passage for the travel ofthe oil surrounded by the heated walls of the tubular conduit, andpresenting also an inner tubular passage providing a counter-flow pathof travel for the oil within said annular passage, wall meansintermediate the annular and the tubular passages of each conduitconstructed and arranged substantially t0 equalize the flow velocity insaid passages and communicating connections between successive conduits.

4. In a high temperature vapor-phase oil cracking still, the combinationwith a heating chamber, of a series of tubular conduits in said chamber,each conduit lpresenting an annular passage for the travel of the oilsurrounded by the heated walls of the tubular conduit, and presentingalso an inner tubular passage providing a counter-how path of travel forthe oil within said annular passage, and communicating connectionsbetween successive conduits, said conduits including internal meanswhereby the cross sectional areas of their annular passages and of theirinner tubular passages are made approximately the same and the flowvelocities therein are substantially equalized while affording arelatively large circumferential external surface for the annularpassages to provide a correspondingly high capacity for the transfer ofheat to the oil in the annular passage.

5. In aV high temperature vapor-phase oil crackingstill, the combinationwith a combustion chamber, of a heating chamber, and a series ofconnected tubular conduits, veach comprising concentrically arrangedtubes providing an outer annular passage for the travel of the oil, aninner communicating passageto provide a counterflow path of travelforthe oil inl the same conduit, and tubular wall means intermediate theannular and the inner passages of each conduit for promoting the iiowvelocity in the annular passage thereof.

6. In a high temperature vapor-phase oil cracking still, the combinationwith a heating chamber, of a series of tubular conduit elements exposedto the heat in said chamber, said conduit elements each presenting aninner passage for one direction of oil travel therein, each conduitelement also presenting an annular passage surrounding and connectingterminally with said inner passage and itself surrounded by the heatexposed wall of its conduit element, said annular passages providing foroil travel therein oppositely to the travel direction in the innerpassages of the corresponding conduit elements, each conduit elementhaving its annular passage connected to the annular passage of anadjacent conduit element and having its inner passage connected to theinner passage of another adjacent conduit element and tubular wall meansintermediate the annular and the inner passages of each conduit forpromoting the flow velocity in the annular passage thereof.

7. In a high temperature vapor-phase oil cracking still, in combination,a heating chamber, a tubular conduit in said chamber, said conduit beingclosed at one end and having its `outer Wall exposed to the heat of saidchamber, said conduit having an inner tubular member opening into itnear its closed end, and said conduit also having an intermediatetubular member disposed between said inner member and the heatexposedconduit Wall, said intermediate member being closed to the travel of thegas through it and being disposed to afford an annular passage ofrelatively small cross section between it and said heat-exposed Wall ofthe conduit.

8. In a gas generator, a heating chamber, a tubular conduit having aclosed end and having its outer wall portion exposed to the heat of saidchamber, said conduit comprising an outer tubular member presenting saidheat-exposed wall, an inner tubular member opening into said outermember near the closed end of the conduit, and an intermediate tubularmember between the inner and outer members, closed to the travel of thegas through it but positioned to afford an annular passage of relativelysmall cross section between it and the outer member.

HENRY BAETZ.

